Techniques of storing supplementary information representing the state of a device at the time of photographing together with photograph data and schemes of encoding/encrypting the supplementary information have been conventionally been proposed in Japanese Patent Laid-Open Nos. 06-318373, 07-303239, and the like. In these proposals, to add and store supplementary information, pieces of supplementary information are put together for each type or the like, and an information structure for adding and storing the supplementary information for each unit is generated.
Consider a case wherein pieces of supplementary information are stored by various devices or schemes. Even for pieces of supplementary information of the same item, generally, various expression forms or encoding/encryption schemes appropriate for the respective devices and control schemes are actually present. However, the above-described supplementary information storing methods can cope with only one expression form or encoding/encryption scheme. In the scheme that allows only one form, supplementary information only needs to cope with that single structure or expression form. However, the characteristic feature of each device or each control scheme is lost.